If I am reading this right, it's the same idea as caseless ammo, just has a new name.

Traditional bullet cartridges have a bullet seated roughly halfway inside a brass shell casing, with gunpowder inside the casing. By contrast, the new rifle uses a 6.5-millimeter polymer-cased telescoped bullet. Telescoped rounds feature a bullet completely encased in a polymer shell, like a shotgun, with gunpowder surrounding the bullet in the shell.

The result is a cartridge that doesn't use brass, a considerable savings in weight. According the Kit Up! blog, telescoped ammunition is about 40 percent lighter than traditional ammunition. Textron could have channeled this weight savings into making lighter ammunition, but instead it chose to make new ammunition that packs a bigger punch. The rifle—and 20 rounds of ammunition—weighs a total of 9.7 pounds. By contrast, the standard M4A1 (pictured above) and 30 rounds of ammunition weigh 8.74 pounds.